Note:
Manipulating the PayPal Website Payments button takes some familiarity
with HTML. If you are not comfortable editing your HTML code by hand,
please create new buttons via the Shopping Cart Button Factory.

Before you begin:

Unlike
a PayPal Website Payments button, where all fields are optional, the
PayPal Shopping Cart requires the item_name and amount fields. If you
did not use either of these fields when you created your PayPal Website
Payments button, please create new buttons via the PayPal Button
Factory.

The current HTML code for your PayPal Website Payments button should look similar to this:

9. Remove
the original PayPal Website Payments HTML code and paste the code you
just created into your website's HTML code. A PayPal 'Add To Cart'
button will appear on your website instead of your original Single Item
Purchase button.

10. To complete
your implementation of the PayPal Shopping Cart, you will still need to
add a 'View Cart' button to your website. To create a 'View Cart'
button, create a regular 'Add to Cart' button on the PayPal Shopping Cart Button Factory. On the second page of the PayPal Shopping Cart Button Factory, you will find the code for your 'View Cart' button.